Heat transfer in condensing systems

The condensate-film heat-transfer coefficients on the exterior of a tube under conditions of inundation, vapour shear and the presence of non-condensing gas may be estimated from the equations which are reviewed in the paper, assuming that the conditions surrounding the tube are known. Estimating these conditions in a large condenser is a problem of some complexity and computer programs for determining these conditions are discussed. Methods for estimating rates of condensing inside tubes with stratified or annular flow are reviewed and the changes in pressure drop resulting from condensation are examined. Surfaces for enhanced condensation include those treated or designed to give drop-wise condensation and those shaped to give locally-thin films under the influence of surface tension. The theories underlying both of those methods of enhancement are discussed and the results which can be achieved are reviewed